1. Field of the Invention
The present invention relates to a method for attaching a lead part and a shield case to a printed circuit board and a method for attaching a chip part, a lead part and a shield case to a printed circuit board.
2. Background of the Invention
A conventional method for attaching a lead part and its shield case to a printed circuit board and a conventional method for attaching a chip part, a lead part and a shield case to a printed circuit board will next be described with reference to FIGS. 1A to 1J.
A process shown in FIG. 1A will first be explained. Reference numeral 1 designates a printed circuit board. A wiring pattern (not shown) is formed on at least one face (an upper side face in FIG. 1A) of the printed circuit board. A aperture 1h and a slit 1s are formed in this printed circuit board 1. A lead 4L of each of plural lead parts (only one lead part 4 is shown in FIGS. 1A to 1J) 4 described later is inserted into the aperture 1. The printed circuit board 1 is cut and the plural lead parts 4 and chip parts 2 corresponding to these plural lead parts 4 are soldered to the individual printed circuit board 1. One portion of a shield case 5 is fitted into the slit 1s.
A cream solder is printed to one portion of predetermined plural pairs of wiring patterns on the one face of such a printed circuit board 1 by using a soldering printer. Plural chip parts (only one chip part is shown in FIGS. 1A to 1J) 2 is mounted onto each printed cream solder (not shown in the figure) by using a mounting device. The printed circuit board 1 mounting these plural chip parts 2 thereonto is put in a reflow furnace and is heated. The solder is melted and is then cooled. Thus, the plural chip parts 2 are soldered to one portion of the plural pairs of wiring patterns of the printed circuit board 1.
Processes of FIGS. 1B and 1C will next be explained. In the process of FIG. 1B, a solder 3 is coated on one portion of the wiring patterns on one face of the printed circuit board 1 by using a solder coating device in the vicinity of the aperture 1h into which the lead 4L of each of the plural lead parts 4 is inserted. In the process of FIG. 1C, the printed circuit board 1 is reversed such that the one face of the printed circuit board 1 is located on a lower side as shown in FIG. 1C.
In a process of FIG. 1D, the plural lead parts 4 are mounted onto the other face (an upper side face in FIG. 1D) of the printed circuit board 1 such that the lead 4L of each of the plural lead parts 4 is inserted into the aperture 1h of the printed circuit board 1 manually or using a mounting inserting device. Each lead 4L enters the solder 3 on the one face of the printed circuit board 1.
In a process of FIG. 1E, the printed circuit board 1 on which mounted are the plural lead parts 4 is put in the reflow furnace and is heated. Thus, the solder 3 is melted and is then cooled. Thus, the plural lead parts 4 are soldered to one portion of predetermined wiring patterns of the printed circuit board 1 together with the plural chip parts 2.
In a process of FIG. 1F, the printed circuit board 1 is cut and divided by using a substrate divider at each of plural lead parts 4 and chip parts 2 respectively corresponding to these plural lead parts.
In a process of FIG. 1G, a shield case 5 is fitted and attached to an individual printed circuit board 1 to which the lead parts 4 and the chip parts 2 corresponding to these lead parts 4 are respectively soldered.
After the process of FIG. 1G, plural individual assembly blocks each attaching the shield case 5 thereto are positioned at a predetermined position of a carrier and are attached so that the assembly blocks are formed. This process is not shown in FIG. 1G.
In a process of FIG. 1H, a portion of a claw 5N described later as one portion of the shield case 5 of each of the plural individual printed circuit boards 1 on the carrier and one portion of a land constructed by a conductive layer on one face of each of the individual printed circuit boards 1 are respectively coated with solder 6 by using the solder coating device.
In a process of FIG. 1I, the claw 5N of the shield case 5 of each of the plural individual printed circuit boards 1 on the carrier is folded on a side of each of the individual printed circuit boards 5 by using a clincher.
After the process of FIG. 1I, the plural individual assembly blocks are detached from the carrier although this detachment is not illustrated in this figure.
In a process of FIG. 1J, the individual assembly blocks are reversed and are put in the reflow furnace and are heated. Thus, the solder 6 is melted and is then cooled. Thus, it is possible to obtain a circuit block in which the shield case 5 is soldered to each of the individual printed circuit boards 1 having the soldered chip parts 2 and the soldered lead parts 4. In addition to the soldering of the shield case, leads of a through capacitor of a case assembly, connector terminals, etc. are also similarly soldered. For example, this circuit block is a high frequency block formed of a tuner and an intermediate frequency amplifier.
This conventional method for attaching the lead part and its shield case to the printed circuit board has the following drawbacks.
The soldering process of leads of the lead parts to the wiring pattern of the printed circuit board and the shield case thereto using the reflow furnace is a separate process so that the number of processes is increased.
Each of the individual printed circuit boards must be attached to the carrier when a portion between a claw of one portion of the shield case and a land of each of the printed circuit boards is coated with the solder by the solder coating device to solder the shield case to each of the individual printed circuit boards. Further, each of the individual printed circuit boards must be detached from the carrier when each of the printed circuit boards and the shield case are put in the reflow furnace to melt the solder. Accordingly, the number of processes is increased.
When each of the plural individual printed circuit boards attaching the shield case thereto is attached to the carrier and the portion between the claw of one portion of the shield case and the land on a side of the slit 1s of each of the printed circuit boards is coated with the solder by the solder coating device, drawbacks exist in that it is difficult to set attaching and coating conditions and a coating accuracy is low.
A slanting cut nozzle or a special nozzle is required as a nozzle for coating the solder around the shield case in the solder coating device. Accordingly, there is also a drawback of an increase in price of the solder coating device.
A portion between the land of a printed circuit board and the claw of the shield case is coated with the solder by inserting the nozzle for coating the solder into the shield case. Further, portions between the wiring pattern of the printed circuit board and leads of a through capacitor, connector terminals, etc. are coated with the solder such that the leads and the terminals, etc. are inserted into the nozzle. Accordingly, the nozzle may be damaged, etc. Therefore, problems exist in that repair work must be required and a manufacturing line is stopped and so on.